Structure‐function analysis of human l‐prostaglandin D synthase bound with fatty acid molecules

Abstract

ABSTRACT Human prostaglandin D synthase (L‐PGDS) is a lipocalin‐type enzyme involved in the metabolism of arachidonic acid and plays a key role in the regulation of sleep, allergy, pain sensation, and the development of male reproductive organs. Here, using a combination of crystallographic, biochemical, mu‐tagenesis, and kinetic studies, we have gained insights into the mode of ligand binding by human L‐PGDS and have identified residues involved in catalysis. Interestingly, structural evidence reveals that 2 molecules of fatty acids, one molecule each of oleic and palmitoleic acid, bind inside the β barrel. The oleic acid is buried and binds in a highly basic patch in proximity to the catalytically critical Cys65, mimicking the binding of prostaglandin H 2 . The palmitoleic acid sits in a relatively neutral region with very few interactions with the protein. Mutating Met64, Leu79, Phe83, or Leu131 to alanine reduced the catalytic efficiency by almost 10‐fold, while K59A and Y149A mutations enhanced the catalytic efficiency by < 2‐fold. Met64 seems to function as a kinetic clamp, pushing the thiol group of Cys65 close to the site of nucleophilic attack during catalysis.—Zhou, Y., Shaw, N., Li, Y., Zhao, Y., Zhang, R., Liu, Z.‐J. Structure‐function analysis of human l‐prosta‐glandin D synthase bound with fatty acid molecules. FASEB J. 24, 4668–4677 (2010). www.fasebj.org